Overwintering concerns...

[brewmeister83]

Hi All,

Since this is my first year overwintering a Chinese Elm (smooth lace-bark variety) up North I had a couple of concerns. First off, I bought this elm earlier in the year from Miami Tropical Bonsai in Florida. I've let it stay outside up here in CT all year, and even though we've had a couple of frosts, the tree is still holding onto some green leaves at the branch tips.

I have a cold frame set up to overwinter my native and evergreen plants, but would this work for the elm if I mulched the pot heavily?

Or, since this is it's first winter in a much colder climate (as far as I know it has only ever been in a subtropical climate in China before being moved to Florida), should I acclimate it to the colder temps over a couple seasons?

My thought here is to wait till complete leaf drop, then move it into an unheated room in my house that gets down near 40, then next year put it into the cold frame where it will get into the 20-30's

Has anyone who also lives "up North" done this with a tropical grown elm? Any thoughts and suggestions are greatly appreciated...

 

[ABCarve]

I'd put it with the rest of your dormant trees. I had one that I left in my unheated garage that was warm enough for the tree to break dormancy enough times to slowly kill it. It will eventually drop its leaves. Mine would hold onto to many of them for the winter and drop them finally as it pushed new growth in the spring, somewhat like an oak.

 

[brewmeister83]

I'd put it with the rest of your dormant trees. I had one that I left in my unheated garage that was warm enough for the tree to break dormancy enough times to slowly kill it. It will eventually drop its leaves. Mine would hold onto to many of them for the winter and drop them finally as it pushed new growth in the spring, somewhat like an oak.

Thanks for the input, I've gotten pretty attached to the tree and have lots of plans for it. I'd just hate to lose it after it regained its strength this year.

BTW...
What kind of oak, pin oak or some non-native like Q. suber? Curiosity got the better of me

 

[cmeg1]

I have read that the smooth bark Chinese elms are less frost hardy and need to be kept above freezing.That is what Peter Chan sais' in his book.Like let go dormant ,but just 35-40 F.

 

[ABCarve]

BTW...
What kind of oak, pin oak or some non-native like Q. suber? Curiosity got the better of me

Robur or English Oak

 

[brewmeister83]

I have read that the smooth bark Chinese elms are less frost hardy and need to be kept above freezing.That is what Peter Chan sais' in his book.Like let go dormant ,but just 35-40 F.

Yeah, I had read that too but from a different source, while other sources said that they can survive unprotected in zone 5. With conflicting information and the publications I read being either from another country or at least 10 yrs old (gotta' take climate change into account) I figured asking someone who's done it before would be a better direction.

Since I also have some trident and kor. hornbeam seedlings that had a rough go earlier this year I was thinking of getting a soil warming cable for one side of my cold frame anyway. maybe I'll stick this elm over with them too.

 

[M. Frary]

I have never heard of a soil warming cable but was thinking of using electrical heat tape like they use to keep water pipes from freezing in the winter. Might be.cheaper and easier to find.

Mike Frary

 

[cmeg1]

I have also read that low intensity lighting can be used to keep trees warm ,like a fluorescent.The light does not disturb the trees when out of leaf or dormant.It was described in the 'pines' book from stone lantern.

 

[ABCarve]

Yeah, I had read that too but from a different source, while other sources said that they can survive unprotected in zone 5. With conflicting information and the publications I read being either from another country or at least 10 yrs old (gotta' take climate change into account) I figured asking someone who's done it before would be a better direction.

Since I also have some trident and kor. hornbeam seedlings that had a rough go earlier this year I was thinking of getting a soil warming cable for one side of my cold frame anyway. maybe I'll stick this elm over with them too.

I would watch out for the warming cable...could be too warm. Do they have a thermostat? If you're really worried I would take Peter Chan advise 35-40. That is still dormant temps.

 

[brewmeister83]

I would watch out for the warming cable...could be too warm. Do they have a thermostat? If you're really worried I would take Peter Chan advise 35-40. That is still dormant temps.

The warming cable idea came from Harry Harrington at bonsai4me.com - he puts a few inches of sand over it so it keeps the roots around 40 degrees or so - says he uses it for trees that are sensitive to root freeze like trident maples and newly separated airlayers. You can find a 36' one on amazon for about 35$, so I figured it was worth a shot.

 

[GrimLore]

I am pretty certain Winter in China varies a bit by area but it does get very cold - I found this just now and it seems correct http://www.mapsofworld.com/china/china-weather.html The reason I am piping in on this is I winter all Elms, Maples, Oak, Black Walnut, Black Cherry, Apple, Pear, Mulberry and Hornbeam the same and always have the best success if they are mulched in and protected from wind. Never saw the cold to be the problem.

Grimmy